1. Field of the Invention
The present invention is related to a novel acquisition and tracking controller for a communications receiver. More particularly, the present invention relates to a novel programmable acquisition and tracking controller for pseudo noise (PN) direct sequence spread spectrum modulated codes.
2. Description of the Prior Art
Heretofore, analog controllers used in communications receivers to acquire and track PN spread spectrum coded data were known. Such analog controllers measured the correlation of the received PN code and the PN code generated by the controller over a fixed detection time, and generated a voltage level indicative of the correlation of the two PN codes. Such analog controllers employed fixed algorithms for acquisition, tracking and reacquisition based on a comparison of the aforementioned voltage level with a threshold that was preset to a fixed value in such prior art devices.
Such analog receivers also included carrier frequency locking loops and phase locking loops as well as clock timing loops which were controlled by error signals produced by the receiver demodulation circuits and controlled by the output of the acquisition and tracking controllers.
Heretofore digital tracking loops for frequency phase and clock timing have been proposed. Such prior art proposed circuits were not programmable and flexible nor were they intended to be manufactured as a single system on one very large scale integrated circuit chip.
It would be highly desirable to provide a remotely programmable digital acquisition and tracking controller as part of a digital communications receiver suitable for implementation on one very large scale integrated circuit chip.